Configuration for Detecting a Physical Parameter at a Stack of Sheets Lying on Top of One Another

ABSTRACT

A configuration for detecting a physical parameter at a stack of sheets resting on top of each other obtains signals from inside a stack in a wireless manner. At least one sensor that responds to changes in the parameter, is disposed between two sheets in the stack and is connected to a stationary evaluation unit. The sensor and the evaluation unit are connected by a wireless connection.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. §119, of GermanPatent Application DE 10 2007 020 975.6, filed May 5, 2007; the priorapplication is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a configuration for detecting a physicalparameter at a stack of sheets resting on top of each other. Theconfiguration includes at least one sensor that responds to changes inthe parameter, is inserted between two sheets in the stack and isconnected to a stationary evaluation unit.

In sheet-fed printing presses, it is known to control driers as afunction of measured values of temperature and humidity. Sensorsdisposed on a flat mount constructed like a blade or rod are used tomeasure the temperature and the humidity in a delivery stack. Duringprinting, the mount, also known as a stack blade, is inserted betweenthe upper sheets of the stack to obtain readings from inside the stack.Lines connect the sensors to a power supply and to an evaluation unitfor evaluating the measured values. Inserting and retracting the stackblade may cause damage to the sheet surface and to a printed image.

It is known to use sensors that are equipped with a transponder in orderto detect physical parameters at moving parts or in closed spaces. Themeasured values are transmitted to a stationary evaluation unit througha wireless connection. Power supply lines or signal lines are notrequired.

German Published, Non-Prosecuted Patent Application DE 10 2006 036 510A1 discloses a control device for a drier. The control device processessignals that indicate the temperature and humidity of sheets. Thesignals are transmitted by wireless sensors that revolve on a chainconveyor for conveying the sheets. The sensor is equipped with athermoelectric converter that is directed to a source of thermalradiation of the drier for power supply purposes.

German Published, Non-Prosecuted Patent Application DE 101 44 103 A1discloses obtaining operating parameters such as temperature or humidityof a roller or cylinder through the use of a wireless sensor. The sensorsignals are used to control a machine or installation.

BRIEF SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a configurationfor detecting a physical parameter at a stack of sheets lying or restingon top of one another, which overcomes the hereinafore-mentioneddisadvantages of the heretofore-known devices of this general type andwith which signals can be obtained from inside the stack in a wirelessmanner.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a configuration for detecting a physicalparameter at a stack of sheets resting on top of each other. Theconfiguration comprises at least one sensor inserted between two sheetsin the stack for responding to changes in the parameter, as well as astationary evaluation unit. A wireless connection is provided betweenthe at least one sensor and the evaluation unit.

The sensor is used to directly or indirectly detect a desired physicalparameter inside the stack. A sensor sensing temperature and/or humiditychanges can be used to control a drier in a printing press. The signalsof a sensor sensing pressure changes can be used to determine the heightof the stack, the application of ink, varnish, dampening solution andpowder. The signals of the pressure sensor can be used to obtainactuating signals for a device for exchanging a stack and signals forcontrolling the application of ink, varnish, dampening solution andpowder. A device positioned adjacent the stack may be provided forinserting the sensor between two sheets in the stack.

In accordance with another feature of the invention, the wirelessconnection between the sensor and the evaluation unit may be a radioconnection. Alternatively, the wireless connection may be an opticalconnection or an acoustic connection.

In accordance with a concomitant feature of the invention, it isfurthermore possible for the sensor to be a microsensor to be placed ona sheet before the sheet is deposited on the stack or while the sheet isbeing deposited on the stack. The outer dimensions of such a microsensorare less than 1 mm. When the stack is transferred to a furtherprocessing station, the microsensor remains in the stack. An autarkicmicrosensor is capable of continuously providing signals of the physicalparameter. The temperature and/or humidity in the stack, in particular,can be measured continuously.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a configuration for detecting a physical parameter at a stack ofsheets lying on top of one another, it is nevertheless not intended tobe limited to the details shown, since various modifications andstructural changes may be made therein without departing from the spiritof the invention and within the scope and range of equivalents of theclaims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE VIEW OF THE DRAWING

The FIGURE of the drawing is a diagrammatic, perspective view of a stackof sheets and a configuration for measuring temperature in the stack ofsheets.

DETAILED DESCRIPTION OF THE INVENTION

Referring now in detail to the single FIGURE of the drawing, there isseen a diagrammatic representation of a configuration for measuringtemperature in a stack 1 in a delivery of a sheet-fed printing press.The stack 1 is formed of a plurality of sheets 2 stacked on top of eachother. The sheets 2 carry a printed image. The sheets pass through adrier 3 before they are deposited on the stack 1. The drier 3 isconnected to a control unit 4 for processing signals of measured valuesindicating the temperature in the stack 1. The measured signals areobtained by sensors 5.1-5.4. The strip-like sensors 5.1-5.4 have beeninserted into the stack 1 through the use of an inserting device 10 thatinserts the sensors 5.1-5.4 in such a way that a respective temperaturemeasuring element 6 is placed between two sheets 2 at distances a and bfrom lateral surfaces of the stack 1 and at a distance c from eachother. Ends of the sensors facing away from the measuring element 6project from a lateral surface 7 of the stack. Each of these ends has anantenna of a transponder for a signal of the measured temperature. Thetransponders are autarkic in terms of power supply. The control unit 4is connected to a transmitter/receiver unit 8. The transmitter 8 isactivated to read out the transponders. The transponder returns therespective signal for the measured temperature to the receiver unit 8.There are wireless connections 9 between the transmitter/receiver unit 8and the transponders.

1. A configuration for detecting a physical parameter at a stack ofsheets resting on top of each other, the configuration comprising: atleast one sensor inserted between two sheets in the stack for respondingto changes in the parameter; a stationary evaluation unit; and awireless connection between said at least one sensor and said evaluationunit.
 2. The configuration according to claim 1, wherein said wirelessconnection is a radio link between said at least one sensor and saidevaluation unit.
 3. The configuration according to claim 2, wherein saidat least one sensor includes a transponder.
 4. The configurationaccording to claim 3, wherein said at least one sensor is strip-shaped,and said transponder includes an antenna projecting from the stack. 5.The configuration according to claim 1, wherein the physical parameteris temperature, and said at least one sensor responds to temperaturechanges in the stack.
 6. The configuration according to claim 1, whereinthe physical parameter is humidity, and said at least one sensorresponds to humidity changes in the stack.
 7. The configurationaccording to claim 1, wherein the physical parameter is pressure, andsaid at least one sensor responds to pressure changes in the stack. 8.The configuration according to claim 1, wherein the stack is disposed ina delivery of a sheet-fed printing press having a conveying path for thesheets, a drier disposed in the conveying path, and a control unit forthe drier, and said evaluation unit is connected to the control unit. 9.The configuration according to claim 8, which further comprises a deviceassociated with the stack for inserting said at least one sensor. 10.The configuration according to claim 1, wherein said at least one sensoris a microsensor.
 11. The configuration according to claim 10, whereinsaid at least one sensor has outer dimensions of less than 1 mm.